oil leak main seal or oil pan gasket
 

I have a 2002 ford f150 xlt v6 that is leaking oil and has been for a long time I would like to get it fixed but I'm not sure what is actually leaking I have been told it was both the rear main seal and the oil pan gasket and another mechanic said it's just the oil pan gasket and yet another said it's only the rear main seal. Both parts aren't very costly but the labor is outrageous. My girlfriend is a mechanic so I think she could fix it any feedback or advice?

What I would suggest is really cleaning area where the oil has accumulated (brake clean will be your friend) and to check on it every other day to see if it starts leaking again. With the area clean it may help to narrow down where the leak is coming from. If you're really lucky it may be oil leaking from the back of the valve covers, but it'll be hard to diagnose until you get everything cleaned off and start monitoring it.

If this is an automatic transmission, there is a rubber plug in the bottom of the bellhousing that can be removed. If it is wet with oil inside the bellhousing then it may be the rear main going out. If it's fairly dry then I would probably be suspecting the oil pan or elsewhere.

If it is the oil pan and this is a 2WD truck then it's going to a pain to get the oil pan out due to the crossmember being in the way. More than likely you will have to lift the engine up quite a ways for clearance. If it is a 4X4 truck then the front axle can be dropped out of the way and the oil pan will be easier to remove/replace.

How much oil is it leaking on the ground? How much is the engine using between oil changes?